They're the bane of pilots and moviegoers, but lasers have become an essential part of everyday life. They facilitate everything from high-speed communications, to vision-saving surgeries, to super-villain plots for world domination. But how in the hell do they get that beam of light so intense and so focused?

As EngineerGuy Bill Hammack explains, it involves trapping light inside a specific medium, between a couple of mirrors, until the waves (or particles) all line up and escape through a pinhole opening. When they leave, it's kind of like soldiers marching in single file, which creates that incredibly intense beam that's been harnessed for endless applications since the first laser was created way back in 1960. [YouTube]